Benzaldehydes have important applications in industry, and two processes are known for producing such benzaldehydes from benzonitriles. One of them is disclosed in Japanese Patent Publication No. 6326/66 and it consists of catalytic reduction of benzonitriles in the presence of lead or lead ions in an acid solvent using a Raney nickel catalyst. But the yield of benzaldehydes produced by this method is not necessarily high. The other process is described in P. Tinapp, Chem. Ber., 102, 2770 (1969) and consists of catalytic reduction of benzonitriles in the presence of a Raney nickel catalyst in a mixed solvent of tetrahydrofuran and water. But this method also has low benzaldehyde yields due to the production of by-products such as benzyl alcohol and benzylamine.